Comment by ideophobia

Purely my opinion and speculation here, but I'd say the things that stick out to me are the timing and avoidance of random casualties for one. This is a hallmark used by the IRA and the ETA in Spain to inflict damage upon the government without damaging the people, so to speak. The use of an RV also stands out to me, I don't recall many VBIEDs associated with foreign terrorists using that type of vehicle in the US, while I do recall RVs being a common tool in militia groups for movement, travel, storage, etc. Some other things stuck out to me watching videos of the explosion, but it's hard to say anything definitive until more evidence is released.